This refrigeration technique was primitive and simple, but it worked so well that people used it from thousands of years ago until the 19th century.
The ice needs to absorb heat in order to melt, so ice cellars are built to be cool inside and sealed from the outside. Typically, an icehouse is much like a semi-basement, partially underground and built near natural sources of ice, such as rivers and freshwater lakes, for easy extraction and storage.
At the same time, people will also cover the ice with wood shavings, which have poor thermal conductivity and are considered a heat shield for the ice. This allows the ice to last a few more months, and can even be used for the next winter if handled properly.
Many ancient civilizations went out of their way to use this type of method to store ice, and China was one of them, and did so around 1,000 B.C., with snippets of "chiseling the ice and rushing it on the day of the second, and then nabbing it in the lingering yin on the day of the third," in written records.
The Song Dynasty also set up a special ice well service, dedicated to storing ice. There were also many kinds of chilled food, such as mixing sugar, fruit and juice in the ice, and in the Yuan Dynasty, people added fruit syrup and milk.
The historical traces of ice cellars can also be seen in the names of some streets now:
It is worth mentioning that in China, the equipment for storing ice was very elaborate, such as the "Bingjian", which is often called the ancient refrigerator:
(Bronze Bingjian in the Warring States period)
It is simple and generous in appearance, and the internal mechanism is ingenious. Interestingly, in summer people could fill the Bronze Ice Almanac with ice, so that the wine in the area where it was served would become cooler, which also became a chilled drink to cool down the summer heat;
But if it came to winter, water could be heated up, and the wine would again become warm wine to warm up the body ....
In my opinion, this is not only wisdom, but also art now.
Rome and the Jewish greats also had a penchant for mixing chilled drinks, where Rome would get snow from the mountains and store's it into pits and cover it with similar insulating materials.
But in areas where the air was drier, such as around Egypt, people opted for another form of refrigeration, 'evaporative cooling'.
We know that evaporation absorbs heat and has a cooling function, and this physical phenomenon was discovered by humans a long time ago and used for refrigeration purposes.
(Water evaporating on the ground)
In hot climates, food doesn't stay fresh for very long, and some fruits and vegetables can hardly last more than a week. So people would use this type of technology to make their own food preservation tools, generally known as a zeer.
This is an 'ice' box made up of two clay pots, which some people jokingly call a refrigerator-in-a-pot.
The zeer is simple to use; the smaller jar fits into the larger one, and the gap between the two gets filled with sand.
The next step is to add water to the sand to keep it moist.
At this point the outer canister will usually have multiple holes for air to come out, the inner canister will usually be waterproofed with some local material, and the whole unit will be placed in a ventilated, dry place.
Finally, the vegetables, fruits and some other food items that cannot be pickled will be placed in the internal tank and covered with a wet cloth, and it will be in the refrigerated mode.